#include <iostream>

// this function has external linkage, and can be seen by other files
void sayHi() {
    std::cout << "Hi!\n";
}

// global variable definitions
int g_x { 2 }; // non-constant globals have external linkage by default
extern const int g_y { 3 }; // this extern gives g_y external linkage
extern constexpr int g_z { 5 };